X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=dh.c;h=c37b5386359294f856fb08eaf156a4c2ca586856;hp=91d08ced2dc805a839dcc3bf9b471c6387a2f0bc;hb=c6a3b1f54ccc754be82f0a2ea5b4d60746053a2b;hpb=389070fed67552c613ce5afd3cdb436f8f8c538f diff --git a/dh.c b/dh.c index 91d08ce..c37b538 100644 --- a/dh.c +++ b/dh.c @@ -1,5 +1,6 @@ #include #include +#include #include "secnet.h" #include "util.h" @@ -11,7 +12,7 @@ struct dh { MP_INT p,g; /* prime modulus and generator */ }; -static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen) +static string_t dh_makepublic(void *sst, uint8_t *secret, int32_t secretlen) { struct dh *st=sst; string_t r; @@ -32,9 +33,9 @@ static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen) } static dh_makeshared_fn dh_makeshared; -static void dh_makeshared(void *sst, uint8_t *secret, uint32_t secretlen, +static void dh_makeshared(void *sst, uint8_t *secret, int32_t secretlen, cstring_t rempublic, uint8_t *sharedsecret, - uint32_t buflen) + int32_t buflen) { struct dh *st=sst; MP_INT a, b, c; @@ -113,7 +114,20 @@ static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context, cfgfatal(loc,"diffie-hellman","modulus must be a prime\n"); } } - st->ops.len=mpz_sizeinbase(&st->p,2)/8; + + size_t sz=mpz_sizeinbase(&st->p,2)/8; + if (sz>INT_MAX) { + cfgfatal(loc,"diffie-hellman","modulus far too large\n"); + } + if (mpz_cmp(&st->g,&st->p) >= 0) { + cfgfatal(loc,"diffie-hellman","generator must be less than modulus\n"); + } + + st->ops.len=sz; + + st->ops.ceil_len=(mpz_sizeinbase(&st->p,2)+7)/8; + /* According to the docs, mpz_sizeinbase(,256) is allowed to return + * an answer which is 1 too large. But mpz_sizeinbase(,2) isn't. */ return new_closure(&st->cl); }